Dennis Sakva
Pooh-Bah
Reged: 10/19/04
Posts: 1303
Loc: Kiev, Ukraine
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Bob, seems like the link was truncated by cloudynights forum engine. I replaced it. Try again.
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lukasik
Pooh-Bah
Reged: 10/11/05
Posts: 1048
Loc: Lawrenceville, Georgia
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Thank you so much for the links Dennis.
Regards,
Bob
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roestman
super member
Reged: 12/18/06
Posts: 128
Loc: Houston Texas
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seems very interesting. for everybodys info, you can go to google language tools and translate the page to english or what ever you speak. not allways correct but it can get you through.
http://www.google.com/language_tools?hl=en
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Rick
TAK TOA-150
12.5" RCOS Truss
C9.25 f/10
WO Zenithstar 110
WO Zenithstar 80
SBIG ST-2000XM CFW-9 w/ Astrodons
FLI PDF focuser
OPTEC TCF-S
AO-8
Canon XTI
Takahashi EM-200
Paramount ME
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idahoman
sage
Reged: 11/25/05
Posts: 473
Loc: Idaho, USA
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This is interesting. But, the files are for CorelDraw, which I do not have. Does anyone have them in a different format? And, how do you scale them for different focal lengths?
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A Guy In Idaho
43° 31' N 112° 4' W
4780 ft elevation
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MtnGoat
Pooh-Bah
Reged: 02/18/07
Posts: 1212
Loc: Columbia Gorge, WA
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he posted the ratios on page on, Idahoman
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"Ignorant people think it's the noise which fighting cats make that is so aggravating, but it ain't so; it's the sickening grammar they use." Mark Twain
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cnstarz
professor emeritus
Reged: 12/22/07
Posts: 549
Loc: Kentucky, USA
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Dennis,
I like this focusing mask thanks for the links and info. I'll try to make one like you've pictured, but first I may use the diffraction angles you've given on a mask like this...LINK
I've been experimenting with the three holed Hartman mask and I think breaking up the symmetry with diffraction spikes like you've described will make it more useful.
Regards,
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Matt
Apogee 50mm BB scope
ETX-60 BB
Meade 70-az
5" DIY Newt (wip)
C6-N on CG-4 GEM
Gallery
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Dennis Sakva
Pooh-Bah
Reged: 10/19/04
Posts: 1303
Loc: Kiev, Ukraine
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Hi Matt,
The main advantage of the mask proposed by Pavel is that you see very clearly where are you right now (before focal point, after it) and there two diffraction spikes give nice and easy reference to compare to. The mask at your link provides no such "reference" lines. The picture just gets messy when not in focus. But one thing for sure it's much easier to make and to try.
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Dennis Sakva
Pooh-Bah
Reged: 10/19/04
Posts: 1303
Loc: Kiev, Ukraine
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The are a few free vector based graphic software.
http://www.inkscape.org/download/?lang=en
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cnstarz
professor emeritus
Reged: 12/22/07
Posts: 549
Loc: Kentucky, USA
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Dennis,
I understand your point, I'll give it a try. I see the key to this is to have two elements that are complementary and a third that contrasts Like here ... MASK
And as your pictures show, the ability to gauge in and out focus is enhanced by the diffraction spikes. I've experienced some frustration using just the three circle mask so I'm eager to try this novel design.
Thanks 
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Matt
Apogee 50mm BB scope
ETX-60 BB
Meade 70-az
5" DIY Newt (wip)
C6-N on CG-4 GEM
Gallery
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Jerry3672
Vendor - Quantum Astronomy Products
Reged: 01/20/08
Posts: 498
Loc: Lexington NC
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Dennis, I followed your link to Pavels design. I drew up a DXF file in Pro-E and cut this out on a water jet. I made the mask out of Aluminum and just painted it black. I will test this as soon as the clouds break.
Thanks for passing on the design.
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Meade LXD75-SN-8, SN-10, C11
DSI Pro
Canon XSi 450D unmod
www.spike-a.com Bahtinov Style Focus Mask
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John Wunderlin
Vendor - Spike-a Focusing Mask
Reged: 10/01/04
Posts: 690
Loc: Mineral Point, Wi
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Can't wait to hear your results. This looks like a potential holy grail of focusing. And a business opportunity for someone with machining tools...
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John Wunderlin
Vendor - Spike-a Bahtinov Focusing Mask
Empire Ranch Observatory
Iowa County Astronomers
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Dennis Sakva
Pooh-Bah
Reged: 10/19/04
Posts: 1303
Loc: Kiev, Ukraine
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Wow... Nice! Looks professional  Please let me know how it works for you.
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Jerry3672
Vendor - Quantum Astronomy Products
Reged: 01/20/08
Posts: 498
Loc: Lexington NC
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Thanks, I was going for a professional part. 
John- I do have some nice machine tools and engineering software. I'll have to cut Dennis and Pavel in on the action. Couldn't you just see the look on Pavels face when big royalty checks start rolling in? 
I do think I have an understanding of how the design works, and why you can't just scale it for other size scopes.
The axis is centered for the "left" side and has a precise light block of 50%. The "right" side has a 20 degree angle that is centered to blocked area of the left. The right side has a light block of 40%. The axis of the right open area must align to the center of the left blocked area. If it centered, then the spikes you see when in focus will align correctly.
I don't read Russian, so I had to look a photos and calculations that Pavel posted.
If this works like I think, then it will be simple for me to draw this design for any size scope.
darn clouds  
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Meade LXD75-SN-8, SN-10, C11
DSI Pro
Canon XSi 450D unmod
www.spike-a.com Bahtinov Style Focus Mask
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Joe Bruessow
sage
Reged: 05/31/04
Posts: 312
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This looks really cool... but I have not been ambitious enough to download the translating software... I'll wait until one of you geniuses posts this all in English 
Thanks...
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MtnGoat
Pooh-Bah
Reged: 02/18/07
Posts: 1212
Loc: Columbia Gorge, WA
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not sure how much they'll be, but I'll volunteer for a couple. I tried doing one with card board and X acto knife last night...horrible. way too many long fine cuts, then when removing material one cut doesn't go all the way through and tears the solid piece next to it. After fixing four breaks at less than 25% done, I said &&&$*$## it.
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"Ignorant people think it's the noise which fighting cats make that is so aggravating, but it ain't so; it's the sickening grammar they use." Mark Twain
Edited by MtnGoat (07/31/08 07:17 PM)
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Dennis Sakva
Pooh-Bah
Reged: 10/19/04
Posts: 1303
Loc: Kiev, Ukraine
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Actually it's important to keep lines straight and free of burrs as those will interfere with diffraction pattern making it blurred. If you don't like cutting you may try gluing strips of something opaque on mask template.
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Jerry3672
Vendor - Quantum Astronomy Products
Reged: 01/20/08
Posts: 498
Loc: Lexington NC
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Not reading Russian made it hard to understand what the sketch was trying to say.
i see now.
My lines are very straight.
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Meade LXD75-SN-8, SN-10, C11
DSI Pro
Canon XSi 450D unmod
www.spike-a.com Bahtinov Style Focus Mask
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Dennis Sakva
Pooh-Bah
Reged: 10/19/04
Posts: 1303
Loc: Kiev, Ukraine
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Yeah, cutting with laser or water-jet gives very nice cuts, working with X-Acto knifes (MtnGoat) is hard
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blueman
Vendor Blue Sky Accessories
Reged: 07/20/07
Posts: 1409
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It is too bad that no one is making these for sale!
Blueman
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14.5" Starmaster with ServoCat and Argo Navis
AT 8" RC
TV NP101 f/5.4 APO Telvue .8 Focal Reducer
WO 80mm f/6 APO Televue .8 focal reducer
SBig ST2000xm with CFW-9 filter wheel
Astrodon Gen2 filters RGBL
Baader HA,O-III, H-Beta, S-II Filters
Losmandy G-11 Gemini Auto-guided
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Jerry3672
Vendor - Quantum Astronomy Products
Reged: 01/20/08
Posts: 498
Loc: Lexington NC
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someone will soon
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Meade LXD75-SN-8, SN-10, C11
DSI Pro
Canon XSi 450D unmod
www.spike-a.com Bahtinov Style Focus Mask
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